THERMOANALYTICAL STUDIES ON ALUMINUM-FREE LAYERED SILICATES

Aluminium-free layered silicate hydrates (metal silicate hydrates - M- SH) are an interesting supplement to the well-known zeolite-like porou s materials, due to their large number of catalytic, adsorptive and io n-exchange properties. By means of a combination of X-ray diffraction investigations and several thermo-analytic methods (TG, DSC, TMA) it c ould be shown that the properties of magadiite will be influenced by t he cations located in the interlayer and the morphology of the as-synt hesized magadiite products. In particular, hydration behaviour and pha se transformation behaviour of the magadiite will be affected. Thus, H - and Ce-magadiite are stable up to temperatures of about 800 degrees C, while the as-synthesized Na-forms will loss water irreversible alre ady at about 200 degrees C, will be dehydroxylated, and will be decomp osed structurally at about 400 degrees C.